Semiconductor unit, method of manufacturing the same, and electronic apparatus

ABSTRACT

There are provided a semiconductor unit that prevents connection failure caused by a wiring substrate to improve reliability, a method of manufacturing the semiconductor unit, and an electronic apparatus including the semiconductor unit. The semiconductor unit includes: a device substrate including a functional device and an electrode; a first wiring substrate electrically connected to the functional device through the electrode; and a second wiring substrate electrically connected to the functional device through the first wiring substrate.

BACKGROUND

The present disclosure relates to a semiconductor unit in which a devicesubstrate provided with functional devices such as display devices isconnected to a wiring substrate for external connection, a method ofmanufacturing the semiconductor unit, and an electronic apparatusincluding the semiconductor unit.

In a display including a plurality of display devices on a devicesubstrate, electrodes for external connection are provided in aperipheral region of the device substrate, and the electrodes areconnected to a wiring substrate. The wiring substrate is connected to adrive circuit such as a driver IC, and external signals are transmittedto the display devices.

In recent years, to address increased demand for displays in terms ofreduction in thickness and frame width, and design, a method in which aflexible wiring substrate is used as a wiring substrate, and theflexible wiring substrate is folded along an outer shape of a devicesubstrate, and thus is contained in a housing, is often used (forexample, Japanese Unexamined Patent Application Publication No.2011-108780). A drive circuit connected to the wiring substrate isdisposed on a back surface side of the device substrate. When a flexiblematerial is used for the device substrate of the display, a flexibledisplay is realizable.

SUMMARY

However, in the folded wiring substrate, stress to return back thefolding, that is, spring back occurs. Accordingly, connection failuresuch as detachment of bonding between the wiring substrate and thedevice substrate, and breaking or short circuit of the wirings of thewiring substrate may occur. In particular, the device substrate used fora flexible display is thin, and the wiring substrate is folded with alarge curvature. Therefore, in the flexible display, spring back isincreased and connection failure is more likely to occur.

It is desirable to provide a semiconductor unit that prevents connectionfailure caused by a wiring substrate to improve reliability, a method ofmanufacturing the semiconductor unit, and an electronic apparatusincluding the semiconductor unit.

According to an embodiment of the technology, there is provided asemiconductor unit including: a device substrate including a functionaldevice and an electrode; a first wiring substrate electrically connectedto the functional device through the electrode; and a second wiringsubstrate electrically connected to the functional device through thefirst wiring substrate.

According to an embodiment of the technology, there is provided anelectronic unit including a semiconductor unit. The semiconductor unitincludes: a device substrate including a functional device and anelectrode; a first wiring substrate electrically connected to thefunctional device through the electrode; and a second wiring substrateelectrically connected to the functional device through the first wiringsubstrate.

In the semiconductor unit or the electronic apparatus of the embodimentof the technology, signal transmission between the functional device andexternal circuits (for example, a drive circuit) is performed throughtwo wiring substrates, namely, the second wiring substrate and the firstwiring substrate.

According to an embodiment of the technology, there is provided a methodof manufacturing a semiconductor unit. The method includes: forming adevice substrate including a functional device and an electrode, theelectrode being electrically connected to the functional device; andelectrically connecting a first wiring substrate to the electrode and toa second wiring substrate.

In the semiconductor unit, the method of manufacturing the same, and theelectronic apparatus according to the embodiments of the technology,signal transmission between the functional device and external circuitsis performed using the two wiring substrate. Therefore, the first wiringsubstrate is allowed to be disposed on the front surface side of thedevice substrate, and the second wiring substrate is allowed to bedisposed on the back surface side of the device substrate. Consequently,signals are allowed to be transmitted between the external circuits onthe back surface side of the device substrate and the functional deviceon the front surface side without the wiring substrates being folded,and thus connection failure on the wiring substrate is prevented toimprove reliability.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the technology as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate embodiments and,together with the specification, serve to explain the principles of thetechnology.

FIG. 1 is a plan view illustrating a configuration of a main part of adisplay according to an embodiment of the disclosure.

FIG. 2 is a diagram illustrating an entire configuration of the displayillustrated in FIG. 1.

FIG. 3 is a circuit diagram illustrating a configuration of a pixeldrive circuit illustrated in FIG. 2.

FIG. 4 is a sectional diagram illustrating a configuration of a displayregion illustrated in FIG. 1.

FIGS. 5A and 5B are diagrams each illustrating configurations of a firstwiring substrate and a second wiring substrate illustrated in FIG. 1.

FIGS. 6A and 6B are perspective views each illustrating theconfigurations of the first wiring substrate and the second wiringsubstrate illustrated in FIGS. 5A and 5B.

FIG. 7 is a perspective view illustrating a modification of the firstwiring substrate illustrated in FIGS. 6A and 6B.

FIGS. 8A and 8B are sectional diagrams each illustrating a process in amethod of manufacturing the display illustrated in FIG. 1.

FIG. 9 is a perspective view for explaining curl generated in a flexiblewiring substrate.

FIG. 10 is a perspective view illustrating another modification of thefirst wiring substrate and the second wiring substrate illustrated inFIGS. 5A and 5B.

FIGS. 11A and 11B are perspective views illustrating other examples ofthe first wiring substrate and the second wiring substrate illustratedin FIG. 10.

FIGS. 12A and 12B are perspective views each illustrating a state wherea wiring substrate is connected to a device substrate in a related art.

FIG. 13 is a perspective view illustrating a state where the wiringsubstrate and the device substrate illustrated in FIGS. 12A and 12B arewarped.

FIGS. 14A and 14B are perspective views for explaining an issue of thewiring substrate illustrated in FIG. 13.

FIGS. 15A and 15B are perspective views for explaining a state where thedisplay illustrated in FIG. 1 is warped.

FIG. 16 is a sectional diagram illustrating a configuration of a mainpart of a display according to a modification 1.

FIGS. 17A and 17B are plan views each illustrating a configuration of amain part of a display according to a modification 2.

FIGS. 18A and 18B are perspective views each illustrating an appearanceof an application example 1.

FIG. 19 is a perspective view illustrating an appearance of anapplication example 2.

FIG. 20A is a perspective view illustrating an appearance of anapplication example 3 viewed from a front side thereof, and FIG. 20B isa perspective view illustrating an appearance of the application example3 viewed from a back side thereof.

FIG. 21 is a perspective view illustrating an appearance of anapplication example 4.

FIG. 22 is a perspective view illustrating an appearance of anapplication example 5.

FIG. 23A is a front view of an application example 6 in an open state,FIG. 23B is a side view thereof, FIG. 23C is a front view in a closedstate, FIG. 23D is a left side view, FIG. 23E is a right side view, FIG.23F is a top view, and FIG. 23G is a bottom view.

DETAILED DESCRIPTION

Hereinafter, a preferred embodiment of the technology will be describedin detail with reference to drawings. Note that the description is givenin the following order.

1. Embodiment

A display in which external signals are transmitted through a firstwiring substrate and a second wiring substrate

2. Modification 1

A display including wirings on both surfaces of a second wiringsubstrate

3. Modification 2

A display including a first drive circuit and a second drive circuitthat are intended to drive display devices and collectively provided onone side of a device substrate

[Embodiment]

FIG. 1 illustrates a planar configuration of a main part of a display (adisplay 1) according to an embodiment of the technology. FIG. 2illustrates an entire configuration of the display 1. The display 1 is aflexible display using a flexible substrate for a device substrate 11,and is deformable through, for example, warping, rolling, folding, andthe like. A plurality of display devices 10 (functional devices) that istwo-dimensionally arranged in a matrix is provided in a display region11A at a center (of a surface) on the device substrate 11. For example,a signal line drive circuit 120 and a scan line drive circuit 130 thatare drivers for image display are provided in a peripheral region 11Bsurrounding the display region 11A. Drive signals (external signals)from one or both of the signal line drive circuit 120 and the scan linedrive circuit 130 are transmitted to the display devices 10 through asecond wiring substrate 22, a first wiring substrate 21, and electrodes12. Herein, the description is given on the assumption that the scanline drive circuit 130 is connected to the second wiring substrate 22and the like. Note that FIG. 1 schematically illustrates theconfiguration of the display 1, and an actual size and an actual shapeare not necessary to be the size and the shape described herein.

The display region 11A is provided with display devices 10 and a pixeldrive circuit 150 driving the display devices 10. In the pixel drivecircuit 150, a plurality of signal lines 120A (120A1, 120A2, . . . ,120Am, . . . ) is arranged in a column direction (Y direction), and aplurality of scan lines 130A (130A1, . . . , 130An, . . . ) is arrangedin a row direction (X direction). The display device 10 is provided ineach intersection between the signal lines 120A and the scan lines 130A.Both ends of each of the signal lines 120A are connected to the signalline drive circuit 120, and both ends of each of the scan lines 130A areconnected to the scan line drive circuit 130.

The signal line drive circuit 120 supplies the display devices 10, whichare selected through the signal lines 120A, with a signal voltage of animage signal according to luminance information supplied from a signalsupply source (not illustrated). The signal voltage from the signal linedrive circuit 120 is applied to both ends of each of the signal lines120A.

The scan line drive circuit 130 is configured of a shift resistor andthe like. The shift resistor sequentially shifts (transfers) a startpulse in synchronization with an input clock pulse. The scan line drivecircuit 130 scans, on a row basis, the image signals that are writteninto the display devices 10, and sequentially supplies the scan signalsto each of the scan lines 130A. The both ends of each of the scan lines130A are supplied with scan signals from the scan line drive circuit130. In other words, the electrode 12 is an electrode electricallyconnected to each of the scan lines 130A in the peripheral region 11B.

FIG. 3 illustrates a configuration example of the pixel drive circuit150. The pixel drive circuit 150 is an active drive circuit includingthin film transistors (TFTs) 13A for selection of the display devices10, TFTs 13B for driving of the display devices 10, capacitors(retention capacitors) 13C, and devices 14A for a display layer (adisplay layer 14 described later). In this circuit, the selection TFTs13A, the drive TFTs 13B, the devices 14A, and the capacitors 13C areprovided in positions where the signal lines 120A and the scan lines130A intersect to each other. In the display 1, for example, theelectrode 12 is connected to a gate electrode of the selection TFT 13Athrough each of the scan lines 130A. Connection destinations ofsource-drain electrodes and a gate electrode of each of the selectionTFT 13A and the drive TFT 13B are not limited to those illustrated inFIG. 3, and may be appropriately changed.

As illustrated in FIG. 4, in the display region 11A, a TFT layer 13including the selection TFTs 13A and the drive TFTs 13B, the displaylayer 14, and a counter substrate 15 are provided in this order on afront surface (a first surface) of the device substrate 11. In thedisplay 1, an image is displayed on a counter substrate 15 side.

The device substrate 11 has, for example, a rectangular shape, and isconfigured of a flexible material with a thickness (a thickness in aZ-axis direction, hereinafter, simply referred to as a thickness) ofabout 10 nm to about 100 nm. Specifically, the device substrate 11 isconfigured of a film that is formed of polyethylene terephthalate,polyethylene naphthalate, polyether sulfone, polyetherimide,polyetherether ketone, polyphenylene sulfide, polyarylate, polyimide,polyamide, polycarbonate, cellulose triacetate, polyolefin, polystyrene,polyethylene, polypropylene, polymethyl methacrylate, polyvinylchloride, polyvinylidene chloride, an epoxy resin, a phenol resin, aurea resin, a melamine resin, a silicone resin, an acrylic resin, or thelike, a metal foil, or the like. A thin-layer glass, a thin-layerceramics, and the like that are reduced in thickness to the extent ofshowing flexibility may be used. The device substrate 11 has a frontsurface, a back surface (a second surface) opposing to the frontsurface, and a side surface (a third surface) connecting the frontsurface and the back surface.

To prevent deterioration of the TFT layer 13 and the display layer 14due to moisture or an organic gas, a barrier layer (not illustrated) maybe provided between the device substrate 11 and the TFT layer 13. Thebarrier layer is formed of, for example, AlO_(x)N_(1-x) (where X=0.01 to0.2) or silicon nitride (Si₃N₄).

The TFT layer 13 has a function as a switching device for selecting apixel, and includes a capacitor 13C, wirings of the pixel drive circuit150 (the signal lines 120A, the scan lines 130A, and the like), inaddition to the selection TFTs 13A and the drive TFTs 13B, each of whichhas a gate electrode, a channel layer, and source-drain electrodes. Eachof the selection TFTs 13A and the drive TFTs 13B may be an inorganic TFTconfigured using an inorganic semiconductor layer as the channel layer,or may be an organic TFT configured using an organic semiconductor layeras the channel layer.

The display layer 14 is configured of a plurality of devices 14A, andincludes, for example, pixel electrodes provided for each of the devices14A, a common electrode common to the devices 14A, and a liquid crystallayer, an organic electroluminescence (EL) layer, an inorganic EL layer,an electrophoretic display element, or the like between the pixelelectrodes and the common electrode.

The counter substrate 15 may be formed of a similar material to that ofthe above-described device substrate 11. A damp-proof film to preventinfiltration of moisture to the display layer 14, and an opticalfunctional film such as an antireflection film may be provided on thecounter substrate 15.

The electrodes 12 electrically connected to the display devices 10 areexposed in the peripheral region 11B of the front surface of the devicesubstrate 11. In the embodiment, as illustrated in FIGS. 5A and 5B, thefirst wiring substrate 21 is connected to the electrode 12, and isfurther connected to the second wiring substrate 22 including the driverIC 23 mounted thereon. Accordingly, external signals are transmitted tothe display devices 10 without the wiring substrates being folded. FIG.5A is a perspective view illustrating a state where the device substrate11, the first wiring substrate 21, and the second wiring substrate areconnected to one another, and FIG. 5B is a sectional view taken along aB-B′ line of FIG. 5A.

As illustrated in FIG. 6A, the first wiring substrate 21 and the secondwiring substrate 22 are flexible wiring substrates each provided withwirings (first wirings 21W or second wirings 22W) on one surface of aflexible base material formed of, for example, polyimide film. Althoughwirings may be formed on both surfaces of the base material as a secondwiring substrate 42 described later, provision of the wirings on onesurface facilitates the processes of manufacturing the first wiringsubstrate 21 and the second wiring substrate 22. Moreover, compared withthe case where the wirings are provided on both surfaces, the thicknessof the wiring substrate is allowed to be reduced. The first wiringsubstrate 21 and the second wiring substrate 22 each have a thicknessof, for example, about several tens μm.

A pitch (a distance between wirings) of each of the first wirings 21Wand the second wirings 22W may be constant (FIG. 6A), or may bedifferent between in a region close to one end and in a region close tothe other end as illustrated in FIG. 6B. For example, when the pitch ofthe electrodes 12 and the pitch of the second wirings 22W are differentfrom each other, the difference between the pitches may be adjust in thefirst wirings 21W. In other words, the pitch of the second wirings 22Wis increased, and thus manufacturing of the second wiring substrate 22is facilitated.

The first wiring substrate 21 is provided on a front surface side of thedevice substrate 11, and the second wiring substrate 22 is provided on aback surface side of the device substrate 11. The first wiring substrate21 and the second wiring substrate 22 are in contact with each other onthe outside of the device substrate 11 (FIGS. 5A and 5B). Specifically,a region close to one end of the first wiring substrate 21 and a regionclose to one end of the second wiring substrate 22 in the extending(X-axis) direction are overlapped with the device substrate 11, and aregion close to the other end of the first wiring substrate 21 and aregion close to the other end of the second wiring substrate 22 areexposed to the outside.

The region close to the one end of the first wiring substrate 21 isbonded to an end of the front surface of the device substrate 11, andthe region close to the other end is flared to the outside of the devicesubstrate 11 to cover the side surface (the third surface). The firstwirings 21W of the first wiring substrate 21 are provided to face theelectrodes 12 on the front surface of the device substrate 11, and arein contact with and electrically connected to the electrodes 12.

The second wiring substrate 22 is bonded to the end of the back surfaceof the device substrate 11, and the region close to the other end isflared to the outside of the device substrate 11 while maintaining aplanar state. In other words, the first wiring substrate 21 and thesecond wiring substrate 22 are in contact with each other on the backsurface side of the device substrate 11. The first wiring substrate 21and the second wiring substrate 22 are flared to the outside of thedevice substrate 11 by the extent that electrical connection between thefirst wiring substrate 21 and the second wiring substrate 22 areensured. The second wiring substrate 22 has a width (in the Y-axisdirection) larger than that of the first wiring substrate 21, forexample. In addition, the second wiring substrate 22 is disposed so thatthe end surface thereof is flared to the outer side of the devicesubstrate 11 than that of the first wiring substrate 21.

The second wirings 22W of the second wiring substrate 22 are provided toface the first wirings 21W, and are in contact with and electricallyconnected to the first wirings 21W on the outside of the devicesubstrate 11. In other words, the first wirings 21W located in a regionclose to one end (on the inside of the device substrate 11) face theelectrodes 12, and the first wirings 21W located in a region close tothe other end (on the outside of the device substrate 11) face thesecond wirings 22W. The driver IC 23 (the first drive circuit) isprovided on the second wirings 22W located in a region close to one end(on the inside of the device substrate 11). In other words, a gap forthe driver IC 23 is provided between the second wiring substrate 22 andthe device substrate 11. The driver IC 23 supplies external signals, forexample, scan signals to the display devices 10.

The first wirings 21W are connected to the electrodes 12 and to thesecond wirings 22W through thermal compression bonding with, forexample, an anisotropic conductive sheet (not illustrated) therebetween.The thermal compression bonding enables electrical connection andbonding. The anisotropic conductive sheet is obtained by dispersingparticles into an adhesive layer formed of a resin or the like. Theparticles are metal fine particles or resin particles coated with ametal. The anisotropic conductive sheet is provided between the firstwirings 21W and the electrodes 12, and between the first wirings 21W andthe second wirings 22W, and then thermal compression bonding isperformed. Thus, metal fine particles or the like are in contact withthe first wirings 21W, the electrodes 12, and the second wirings 22W tomake electrical connection. In addition, the adhesive layer in theanisotropic conductive sheet is cured so that the first wiring substrate21 is bonded and fixed to the device substrate 11 and to the secondwiring substrate 22.

As illustrated in FIG. 7, a protective portion 24 covering a part of thefirst wirings 21W, for example, a center portion of the first wirings21W, may be provided on the first wiring substrate 21. The protectiveportion 24 prevents breakage of the first wirings 21W when theelectrodes 12 and the first wirings 21W are connected. When the firstwiring substrate 21 is provided in a region from the front surface tothe side surface of the device substrate 11, a part of the first wiringsubstrate 21 faces a corner configured of the front surface and the sidesurface of the device substrate 11. The protective portion 24 isprovided in a portion facing the corner to prevent damage of the firstwirings 21W. The protective portion 24 is formed of, for example, anacrylic film, a urethane film, an imide film, or photosolder resist. Theprotective portion 24 may be provided on the second wiring substrate 22.In addition, instead of provision of the protective portion 24, chamfertreatment of the corner of the device substrate 11 prevents damage ofthe first wirings 21W.

The display 1 is manufactured in the following way, for example.

First, the above-described TFT layer 13 is formed in the display region11A of the device substrate 11. At the same time of formation of thewirings and the electrodes of the TFT layer 13, the electrodes 12 areformed in the peripheral region 11B. Next, the display layer 14 and thecounter substrate 15 are formed on the TFT layer 13. Consequently, thedevice substrate 11 including the display devices 10 and the electrodes12 on the front surface thereof is formed.

Subsequently, the first wiring substrate 21 is connected to the devicesubstrate 11 (the electrodes 12) and to the second wiring substrate 22using anisotropic conductive sheets through thermal compression bonding.The processes of the thermal compression bonding are performed with useof a thermal compression bonding apparatus 30 including two heads (anupper head 31 and a lower head 32), as illustrated in FIGS. 8A and 8B,for example. First, the anisotropic conductive sheet (not illustrated)is provided between the first wiring substrate 21 and the devicesubstrate 11 and between the first wiring substrate 21 and the secondwiring substrate 22, and then the first wiring substrate 21, the devicesubstrate 11, and the second wiring substrate 22 are sandwiched betweenthe upper head 31 and the lower head 32. Then, when the upper head 31and the lower head 32 are heated, the first wiring substrate 21, thedevice substrate 11, the second wiring substrate 22, and the anisotropicconductive sheets are heated, and thus, electrical connection andbonding are performed therebetween. As illustrated in FIG. 8A, in theprocesses of the thermal compression bonding, with use of the smallupper head 31, connection between the first wiring substrate 21 and thedevice substrate 11 may be performed separately from connection betweenthe first wiring substrate 21 and the second wiring substrate 22.Alternatively, as illustrated in FIG. 8B, with use of the large upperhead 31, both the connections may be performed at the same time. In thecase where there is less possibility that the first wirings 21W and thesecond wirings 22W are damaged by the corner of the device substrate 11or the like, both the connections are favorably performed at the sametime because manufacturing processes are allowed to be reduced. Forexample, when the device substrate 11 is soft, the thermal compressionbonding between the first wiring substrate 21 and the device substrate11 may be performed at the same time of the thermal compression bondingbetween the first wiring substrate 21 and the second wiring substrate22. When the connection between the first wiring substrate 21 and thedevice substrate 11 is performed separately from the connection betweenthe first wiring substrate 21 and the second wiring substrate 22,connection with a small pitch, for example, the connection between thefirst wiring substrate 21 and the device substrate 11 is favorablyperformed first.

Moreover, in the processes of the thermal compression bonding, when athermosetting adhesive layer is provided between the device substrate 11and the second wiring substrate 22, the second wiring substrate 22 isallowed to be fixed to the device substrate 11 in the same process. Thedevice substrate 11, the first wiring substrate 21, and the secondwiring substrate 22 are contacted as close as possible to improveflexibility of the display 1.

To prevent curl of the first wiring substrate 21 and the second wiringsubstrate 22, the thermal compression bonding may be performed in astate where the end of each of the first wiring substrate 21 and thesecond wiring substrate 22 is increased in thickness. As illustrated inFIG. 9, when a wiring substrate (a wiring substrate 20) is decreased inthickness, shape stability is decreased and curl (for example, in anarrow direction of FIG. 9) easily occurs. The curl of the wiringsubstrate 20 may inhibit the processes of the above-described thermalcompression bonding. For example, there are conceivable disadvantagesthat, for example, the wiring substrate 20 is not allowed to be held invacuum contact by the thermal compression bonding apparatus 30, and thewiring substrate 20 is dropped off from the thermal compression bondingapparatus 30 (the upper head 31 and the lower head 32) during theprocesses of the thermal compression bonding. Then, as illustrated inFIG. 10, a thick film portion 22T is provided on the end of the secondwiring substrate 22, thereby preventing the curl of the second wiringsubstrate 22. The thick film portion 22T is provided on the other end(on the outside of the device substrate 11) of the second wiringsubstrate 22, and has a thickness larger than that of the other portionsby about 50 μm, for example. The thick film portion 22T may be formed bystacking the similar material to the protective portion 24, such as anacrylic film, a urethane film, an imide film, and photo solder resist.In addition, the thick film portion 22T may be configured of a dummyelectrode. With such a thick film portion 22T, processes of the thermalcompression bonding is allowed to be performed smoothly. Although thethick film portion 22T may be remained, the thick film portion 22T iscut out along a cut line 22C after thermal compression bonding so thatthe second wiring substrate 22 with uniform thickness is obtainable.

Moreover, as illustrated in FIG. 11A, a thick film portion (a thick filmportion 21T) may be provided on the first wiring substrate 21, inaddition to the second wiring substrate 22. The first wiring substrate21 and the second wiring substrate 22 are provided with the thick filmportions 21T and 22T, respectively, and are subjected to the thermalcompression bonding, and then the thick film portions 21T and 22T arecut out along a cut line 22C. At this time, as illustrated in FIG. 11B,the end surface (the cut surface) of the first wiring substrate 21 andthe end surface of the second wiring substrate 22 are aligned. Only thefirst wiring substrate 21 may have a thick film portion.

The display 1 illustrated in FIG. 1 is completed through the processesdescribed above. Note that, after the device substrate 11 (theelectrodes 12) and the second wiring substrate 22 are electricallyconnected to the first wiring substrate 21, the display layer 14 and thelike may be formed.

In the display 1, the scan signal and the pixel signal are supplied fromthe scan line drive circuit 130 (the driver IC 23) and the signal linedrive circuit 120, respectively, to each of the display devices 10, andthe drive of the display devices 10 is accordingly controlled.Therefore, images are displayed on the counter substrate 15 side.

In the display 1 of the embodiment, the external signals (for example,the scan signal) are transmitted to the display devices 10 through thesecond wiring substrate 22 on the back surface of the device substrate11 and the first wiring substrate 21 on the front surface of the devicesubstrate 11. Specifically, since the wiring substrate is not folded,spring back does not occur in the first wiring substrate 21 and thesecond wiring substrate 22, and thus connection failure is prevented.The detail thereof is described in detail below.

As illustrated in FIG. 12A, in a display (a display 100) in a relatedart, one wiring substrate (a wiring substrate 121) is folded along anouter shape of a device substrate (a device substrate 111), andelectrodes 112 on the front surface of the device substrate 111 areconnected to a drive circuit on the back surface. To reduce a framewidth, the wiring substrate 121 is folded along a portion nearer thedevice substrate 111. In such a wiring substrate 121, stress (springback) intended to restore the wiring substrate 121 from the folded stateoccurs. In the display 100, there is a possibility, due to the stress,of connection failure such as debonding (disconnection) between thedevice substrate 111 (the electrodes 112) and the wiring substrate 121,breaking or short circuit of the wirings of the wiring substrate 121. Inparticular, as illustrated in FIG. 12B, when a display (a display 101)is a flexible display, connection failure may easily occur. This iscaused from the following reasons. In the display 100, a thickness T ofthe device substrate 111 is about 0.5 to about 0.7 mm. In contrast, inthe display 101, a device substrate 111A has a thickness T smaller thanthat of the device substrate 111 by about single digit, or has thethickness T of about several tens μm. In other words, the thickness T ofthe device substrate 111A is substantially equal to the thickness of thewiring substrate 121, and curvature of the wiring substrate 121 isincreased (a radius of curvature is close to zero). Accordingly, thespring back of the wiring substrate 121 is also increased.

In addition, the display 100 is protected by a housing thereof in use,and thus additional external force is not applied to the display 100. Incontrast, the display 101 is subjected to pressure and is deformed inuse. Therefore, in the display 101, the stress applied to the wiringsubstrate 121 is larger than that in the display 100.

Furthermore, as illustrated in FIG. 13, when the display 101 is warpedalong a dashed line (X-axis), for example, distortion (distortion 121D)may occur in the wiring substrate 121.

As illustrated in FIG. 14A, when a paper (a paper 122) folded along afolding portion 122B is warped in an arrow direction, distortion(distortion 122D) occurs (FIG. 14B). This is because force for expansionacts on the outside of the warped paper 122 and force for contractionacts on the inside thereof, and thus stress collects in the foldingportion 122B of the paper 122 to cause the distortion 122D. Thedistortion 122D appears as, for example, unnatural bend which causesbending tendency. The distortion 122D is allowed to be reduced as thethickness of the paper 122 is reduced. However, if the thickness of thepaper 122 is about several tens μm, the distortion 122D is not allowedto be eliminated. The distortion 121D of the wiring substrate 121 occursbased on the similar principle to that of the distortion 122D of thepaper 122, and the distortion 121D may cause breaking or short circuitof the wirings of the wiring substrate 121 or breaking of the basematerial. In addition, when the distortion 121D influences theconnection portion between the device substrate 111A and the wiringsubstrate 121, these substrates may be detached.

In contrast, in the display 1 of the embodiment, the first wiringsubstrate 21 is provided on the front surface side of the devicesubstrate 11 and the second wiring substrate 22 is provided on the backsurface side. Therefore, the external signals are transmitted from thedrive circuit (the driver IC 23) on the back surface side of the devicesubstrate 11 to the display devices 10 on the front surface side withoutthe wiring substrate being folded. Accordingly, spring back does notoccur in the first wiring substrate 21 and the second wiring substrate22, and thus connection failure is prevented. In particular, in thedisplay 1 as a flexible display, although the device substrate 11 isthin and the external force is applied in use, connection failure iseffectively suppressed.

Furthermore, as illustrated in FIG. 15A, when two papers (papers 122-1and 122-2) are bonded at a connection portion 122C and warped in anarrow direction, distortion does not occur (FIG. 15B). In other words,when the display 1 is warped in a similar way, distortion does not occurin the first wiring substrate 21 and the second wiring substrate 22, andthus connection failure caused by the distortion is allowed to besuppressed.

As described above, in the display 1 of the embodiment, the driver IC 23and the display devices 10 are connected through the two wiringsubstrates (the first wiring substrate 21 and the second wiringsubstrate 22). Therefore, it is possible to prevent connection failurecaused by the wiring substrates and to improve reliability. Inparticular, in the display 1 as a flexible display, connection failureis effectively suppressed.

Although modifications of the embodiment will be described below, likenumerals are used to designate substantially like components of theabove-described embodiment, and the description thereof will beappropriately omitted.

[Modification 1]

FIG. 16 illustrates a cross-sectional configuration of a main part of adisplay (a display 1A) according to a modification 1 of the embodiment.The display 1A is provided with a second wiring substrate 42 havingsecond wirings (second wirings 42W) on both surfaces thereof. In thesecond wiring substrate 42, one surface (surface facing the devicesubstrate 11) is in contact with the first wiring substrate 21, and theother surface is mounted with the driver IC 23. Except for this point,the display 1A has the similar configuration to that of the display 1 ofthe embodiment, and the function and the effects of the display 1A aresimilar to those of the display 1.

The second wiring substrate 42 includes second wirings 42W-1 provided onone surface and second wirings 42W-2 provided on the other surface. Thesecond wirings 42W-1 and 42W-2 are connected to each other throughthrough-holes 42H provided on a base material of the second wiringsubstrate 42. In such a second wiring substrate 42, the driver IC 23 isallowed to be provided on a surface opposite to a surface contacted withthe first wiring substrate 21 (on a surface facing the device substrate11). In other words, a gap for the driver IC 23, between the devicesubstrate 11 and the second wiring 42 is not necessary, and the secondwiring substrate 42 is stably fixed to the device substrate 11. Inaddition, the device substrate 11 and the second wiring substrate 42 areclosely bonded to improve flexibility of the display 1.

Moreover, provision of the second wirings 42W on both surfaces preventscurl of the second wiring substrate 42. When the wirings are provided onone surface of the wiring substrate, curl is likely to occur due todifference in coefficient of extension between one surface and the othersurface. On the other hand, in the second wiring substrate 42, thesecond wirings 42W-1 and 42W-2 are provided on both surfaces. Therefore,the difference in coefficient of extension is decreased to preventoccurrence of curl.

[Modification 2]

FIGS. 17A and 17B are top views each illustrating a planar configurationof a display (a display 1B) according to a modification 2 of theembodiment. FIG. 17A illustrates a front surface side of the display 1B,and FIG. 17B illustrates a back surface side thereof. In the display 1B,the signal line drive circuit 120 (the second drive circuit) and thedriver IC 23 (the scan line drive circuit 130) are provided on the sameside (a side in the X-axis direction) of the device substrate 11. Exceptfor this point, the display 1B has the similar configuration to that ofthe display 1 of the embodiment, and the function and the effects of thedisplay 1B are similar to those of the display 1.

In the display 1B, electrodes 16 on the device substrate 11 are drawn toa side (a first side) in the X-axis direction, and the electrodes 12electrically connected to the driver IC 23 are drawn to a side (a secondside) in the Y-axis direction. The electrode 16 applies a signal voltagefrom the signal line drive circuit 120 to the display devices 10 throughthe signal lines 120A. Similarly to the above-described display 1, theelectrodes 12 are connected to the first wiring substrate 21, and thefirst wiring substrate 21 is connected to the second wiring substrate 22(or the second wiring substrate 42). A region close to one end of thesecond wiring substrate 22 is in contact with the first wiring substrate21 on the outside of the device substrate 11 (the second side), and aregion close to the other end of the second wiring substrate 22 extendsto the first side through the back surface side of the device substrate11. The driver IC 23 is mounted in the region close to the other end ofthe second wiring substrate 22. In other words, the signal line drivecircuit 120 and the driver IC 23 are provided on the first side of thedevice substrate 11. As described above, the second wiring substrate 22extends on the back surface side of the device substrate 11, and thesignal line drive circuit 120 and the driver IC 23 are provided on thesame side of the device substrate 11 so that the number of movabledirections of the device substrate 11 is increased and flexibility ofthe display 1 is improved. The second wiring substrate 22 may extend tothe first side in a curved manner (FIG. 17B), or extend straightly.

The above-described display 1 (or the display 1A or 1B) is allowed to bemounted on electronic units illustrated in the following applicationexamples 1 to 6, for example.

[Application Example 1]

FIGS. 18A and 18B each illustrate an appearance of an electronic book.The electronic book includes, for example, a display section 210, anon-display section 220, and an operation section 230, and the displaysection 210 is configured of the above-descried display 1, 1A, or 1B.The operation section 230 may be formed on the same surface (a frontsurface) as that of the display section 210 as illustrated in FIG. 18A,or may be formed on a surface (a top surface) different from that of thedisplay section 210 as illustrated in FIG. 18B.

[Application Example 2]

FIG. 19 illustrates an appearance of a television. The televisionincludes, for example, an image display screen section 300 including afront panel 310 and a color filter 320. The image display screen section300 is configured of the above-described display 1, 1A, or 1B.

[Application Example 3]

FIGS. 20A and 20B each illustrate an appearance of a digital stillcamera. The digital still camera includes, for example, a light emittingsection 410 for flash light, a display section 420, a menu switch 430,and a shutter button 440. The display section 420 is configured of theabove-described display 1, 1A, or 1B.

[Application Example 4]

FIG. 21 illustrates an appearance of a notebook personal computer. Thenotebook personal computer includes, for example, a main body 510, akeyboard 520 for inputting letters and the like, and a display section530 displaying images. The display section 530 is configured of theabove-described display 1, 1A, or 1B.

[Application Example 5]

FIG. 22 illustrates an appearance of a video camera. The video cameraincludes, for example, a main body section 610, a lens 620 for shootingan object, provided on a front side surface of the main body section610, a shooting start-stop switch 630, and a display section 640. Thedisplay section 640 is configured of the above-described display 1, 1A,or 1B.

[Application Example 6]

FIGS. 23A to 23G each illustrate an appearance of a mobile phone. Themobile phone is configured by connecting, for example, an upper housing710 and a lower housing 720 with a connecting section (a hinge section)730, and includes a display 740, a sub display 750, a picture light 760,and a camera 770. The display 740 and/or the sub display 750 are/isconfigured of the above-described display 1, 1A, or 1B.

Hereinbefore, although the technology has been described with referringto the embodiment and the modifications, the technology is not limitedto the above-described embodiment and the like, and variousmodifications may be made. For example, in the above-describedembodiment and the like, the case where the driver IC 23 is the scanline drive circuit 130 has been described. However, the driver IC 23 maybe the signal line drive circuit 120. At this time, for example, theelectrodes 12 are electrically connected to one of the source-drainelectrodes of the selection TFTs 52A through the signal lines 120A. Inaddition, as the other modifications, the electrodes 12 may be connectedto the other wirings (terminals) such as power lines (not illustrated),or a plurality of electrodes 12 each connected to different wirings (forexample, the scan line 130A and the signal line 120A, the scan line 130Aand the power line, or the signal line 120A and the power line) areprovided and combined. Further, the second wiring substrate 22 (thesecond wiring substrate 42) may be electrically connected to the otherelectronic circuits, instead of the driver IC 23.

Furthermore, in the above-described embodiment and the like, the casewhere the pixel drive circuit 150 includes two TFTs (the selection TFTs13A and the drive TFTs 13B) has been described (FIG. 3). Alternatively,one display device 10 may include one or three or more TFTs. Moreover,the display 1 may display images on the device substrate 11 side.

In addition, in the above-described modification 1, the case where thethrough-holes 42H are provided on the second wiring substrate 42 hasbeen described. Alternatively, through-holes may be provided on thefirst wiring substrate 21.

Moreover, in the above-described embodiment and the like, the case wherethe width of the second wiring substrate 22 is larger than the width ofthe first wiring substrate 21 has been illustrated (FIG. 1 and thelike). Alternatively, the first wiring substrate 21 and the secondwiring substrate 22 may have the same width, or the width of the firstwiring substrate 21 may be larger than the width of the second wiringsubstrate 22.

Furthermore, in the above-described embodiment and the like, the casewhere the end surface of the second wiring substrate 22 is located onthe outer side of the device substrate 11 than that of the first wiringsubstrate 21 has been illustrated (FIG. 1 and the like). Alternatively,the end surfaces of the first wiring substrate 21 and the second wiringsubstrate 22 may be aligned, or the end surface of the first wiringsubstrate 21 is located on outer side of the device substrate 11.

In addition, in the above-described embodiment and the like, the casewhere the device substrate 11, the first wiring substrate 21, and thesecond wiring substrate 22 each have a rectangular shape has beenillustrated (FIG. 1 and the like). Alternatively, the substrates mayhave the other shapes such as a square shape and a trapezoidal shape.

Moreover, the material and the thickness of each of the parts describedin the above-described embodiment and the like, the formation method, orthe like are not limited, and the other materials and the otherthickness, or the other formation methods are acceptable.

Furthermore, in the above-described embodiment and the like, the casewhere the semiconductor unit includes the display devices as thefunctional devices has been described. Alternatively, the functionaldevices other than the display device, for example, an image pickupdevice and a solar cell are acceptable.

Note that the present technology may be configured as follows.

(1) A semiconductor unit including:

a device substrate including a functional device and an electrode;

a first wiring substrate electrically connected to the functional devicethrough the electrode; and

a second wiring substrate electrically connected to the functionaldevice through the first wiring substrate.

(2) The semiconductor unit according to (1), wherein

the electrode of the device substrate is in contact with a first wiringof the first wiring substrate, and

the first wiring is in contact with a second wiring of the second wiringsubstrate.

(3) The semiconductor unit according to (1) or (2), wherein

the functional device and the electrode are provided on a first surfaceof the device substrate, and

the first wiring substrate is provided on a first surface side of thedevice substrate, and the second wiring substrate is provided on asecond surface side opposing to the first surface.

(4) The semiconductor unit according to any one of (1) to (3), whereinthe first wiring substrate and the second wiring substrate are incontact with each other on an outside of the device substrate.

(5) The semiconductor unit according to any one of (1) to (4), whereineach of the first wiring substrate and the second wiring substrate isconfigured of a flexible material.

(6) The semiconductor unit according to any one of (1) to (5), whereinthe second wiring substrate is connected to a first drive circuittransmitting external signals.

(7) The semiconductor unit according to (6), wherein

a second wiring is provided on both of a first surface and a secondsurface of the second wiring substrate, the first surface facing a firstwiring of the first wiring substrate, and

the first drive circuit is connected to the second surface of the secondwiring substrate.

(8) The semiconductor unit according to (7), wherein the second wiringon the first surface of the second wiring substrate is connected to thesecond wiring on the second surface of the second wiring substratethrough through-holes provided on the second wiring substrate.

(9) The semiconductor unit according to any one of (1) to (8), whereinthe device substrate is configured of a flexible material.

(10) The semiconductor unit according to any one of (1) to (9), wherein

the device substrate includes a first surface, a second surface, and athird surface, the second surface opposing to the first surface, thethird surface connecting the first surface and the second surface,

the first wiring substrate is provided from the first surface to thethird surface of the device substrate and has a protective portionpartially covering the first wiring, and

the protective portion faces a corner configured of the first surfaceand the third surface of the device substrate.

(11) The semiconductor unit according to any one of (6) to (10), wherein

a second drive circuit is provided on one side of the device substrate,the second drive circuit driving the functional device,

a region close to one end of the second wiring substrate is in contactwith the first wiring substrate on the outside of the device substrate,and a region close to the other end of the second wiring substrateextends to the one side of the device substrate provided with the seconddrive circuit, and

the first drive circuit is connected to the region close to the otherend of the second wiring substrate.

(12) The semiconductor unit according to any one of (1) to (11), whereinend surfaces of the first wiring substrate and the second wiringsubstrate are aligned.

(13) The semiconductor unit according to any one of (1) to (12), whereinthe functional device is a display device.

(14) The semiconductor unit according to any one of (6) to (13), whereinthe first drive circuit is a driver integrated circuit (IC).

(15) An electronic apparatus with a semiconductor unit, thesemiconductor unit including:

a device substrate including a functional device and an electrode;

a first wiring substrate electrically connected to the functional devicethrough the electrode; and

a second wiring substrate electrically connected to the functionaldevice through the first wiring substrate.

(16) A method of manufacturing a semiconductor unit, the methodincluding:

forming a device substrate including a functional device and anelectrode, the electrode being electrically connected to the functionaldevice; and

electrically connecting a first wiring substrate to the electrode and toa second wiring substrate.

(17) The method according to (16), wherein the first wiring substrate iselectrically connected to the electrode and to the second wiringsubstrate after a thick film portion is provided an end of one or bothof the second wiring substrate and the first wiring substrate.

(18) The method according to (17), wherein the thick film portion is cutout after the first wiring substrate is electrically connected to theelectrode and to the second wiring substrate.

(19) The method according to any one of (16) to (18), wherein electricalconnection between the first wiring substrate and the electrode andelectrical connection between the first wiring substrate and the secondwiring substrate are performed at a time.

(20) The method according to any one of (16) to (18), wherein theelectrical connection between the first wiring substrate and the secondwiring substrate is performed after electrical connection between thefirst wiring substrate and the electrode is performed.

The present application contains subject matter related to thatdisclosed in Japanese Priority Patent Application JP 2012-023315 filedin the Japan Patent Office on Feb. 6, 2012, the entire content of whichis hereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations, and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A semiconductor unit comprising: a devicesubstrate including a functional device and an electrode; a first wiringsubstrate electrically connected to the functional device through theelectrode; and a second wiring substrate electrically connected to thefunctional device through the first wiring substrate, wherein the secondwiring substrate is connected to a first drive circuit transmittingexternal signals, wherein a second wiring is provided on both of a firstsurface and a second surface of the second wiring substrate, the firstsurface facing a first wiring of the first wiring substrate, and whereinthe first drive circuit is connected to the second surface of the secondwiring substrate.
 2. The semiconductor unit according to claim 1,wherein the electrode of the device substrate is in contact with thefirst wiring of the first wiring substrate, and the first wiring is incontact with a second wiring of the second wiring substrate.
 3. Thesemiconductor unit according to claim 1, wherein the functional deviceand the electrode are provided on a first surface of the devicesubstrate, and the first wiring substrate is provided on a first surfaceside of the device substrate, and the second wiring substrate isprovided on a second surface side opposing to the first surface.
 4. Thesemiconductor unit according to claim 1, wherein the first wiringsubstrate and the second wiring substrate are in contact with each otheron an outside of the device substrate.
 5. The semiconductor unitaccording to claim 1, wherein each of the first wiring substrate and thesecond wiring substrate is configured of a flexible material.
 6. Thesemiconductor unit according to claim 5, wherein the device substrateincludes a first surface, a second surface, and a third surface, thesecond surface opposing to the first surface, the third surfaceconnecting the first surface and the second surface, the first wiringsubstrate is provided from the first surface to the third surface of thedevice substrate and has a protective portion partially covering thefirst wiring, and the protective portion faces a corner configured ofthe first surface and the third surface of the device substrate.
 7. Thesemiconductor unit according to claim 1, wherein the second wiring onthe first surface of the second wiring substrate is connected to thesecond wiring on the second surface of the second wiring substratethrough through-holes provided on the second wiring substrate.
 8. Thesemiconductor unit according to claim 1, wherein the device substrate isconfigured of a flexible material.
 9. The semiconductor unit accordingto claim 1, wherein a second drive circuit is provided on one side ofthe device substrate, the second drive circuit driving the functionaldevice, a region close to one end of the second wiring substrate is incontact with the first wiring substrate on the outside of the devicesubstrate, and a region close to the other end of the second wiringsubstrate extends to the one side of the device substrate provided withthe second drive circuit, and the first drive circuit is connected tothe region close to the other end of the second wiring substrate. 10.The semiconductor unit according to claim 1, wherein end surfaces of thefirst wiring substrate and the second wiring substrate are aligned. 11.The semiconductor unit according to claim 1, wherein the functionaldevice is a display device.
 12. The semiconductor unit according toclaim 1, wherein the first drive circuit is a driver integrated circuit(IC).
 13. An electronic apparatus with a semiconductor unit, thesemiconductor unit comprising: a device substrate including a functionaldevice and an electrode; a first wiring substrate electrically connectedto the functional device through the electrode; and a second wiringsubstrate electrically connected to the functional device through thefirst wiring substrate, wherein the second wiring substrate is connectedto a first drive circuit transmitting external signals, wherein a secondwiring is provided on both of a first surface and a second surface ofthe second wiring substrate, the first surface facing a first wiring ofthe first wiring substrate, and wherein the first drive circuit isconnected to the second surface of the second wiring substrate.
 14. Theelectronic apparatus according to claim 13, wherein the electrode of thedevice substrate is in contact with the first wiring of the first wiringsubstrate, and the first wiring is in contact with the second wiring ofthe second wiring substrate.
 15. The electronic apparatus according toclaim 13, wherein the functional device and the electrode are providedon a first surface of the device substrate, and the first wiringsubstrate is provided on a first surface side of the device substrate,and the second wiring substrate is provided on a second surface sideopposing to the first surface.
 16. The electronic apparatus according toclaim 13, wherein the first wiring substrate and the second wiringsubstrate are in contact with each other on an outside of the devicesubstrate.
 17. A method of manufacturing a semiconductor unit, themethod comprising: forming a device substrate including a functionaldevice and an electrode, the electrode being electrically connected tothe functional device; and electrically connecting a first wiringsubstrate to the functional device through the electrode; electricallyconnecting the functional device to a second wiring substrate throughthe electrode of the first wiring substrate, wherein the second wiringsubstrate is connected to a first drive circuit transmitting externalsignals, wherein a second wiring is provided on both of a first surfaceand a second surface of the second wiring substrate, the first surfacefacing a first wiring of the first wiring substrate, and wherein thefirst drive circuit is connected to the second surface of the secondwiring substrate.
 18. The method according to claim 17, wherein thefirst wiring substrate is electrically connected to the electrode and tothe second wiring substrate after a thick film portion is provided at anend of one or both of the second wiring substrate and the first wiringsubstrate, wherein the thick film portion is cut out after the firstwiring substrate is electrically connected to the electrode and to thesecond wiring substrate.
 19. The method according to claim 17, whereinelectrical connection between the first wiring substrate and theelectrode and electrical connection between the first wiring substrateand the second wiring substrate are performed at a same time.
 20. Themethod according to claim 17, wherein the first wiring substrate and thesecond wiring substrate are electrically connected after electricalconnection between the first wiring substrate and the electrode isperformed.